GEMSTONE-201: Preplanned primary analysis of a multicenter, single-arm, phase 2 study of sugemalimab (suge) in patients (pts) with relapsed or refractory extranodal natural killer/T cell lymphoma (R/R ENKTL).
Authors: Huiqiang Huang, Rong Tao, Yu Yang, Hong Cen, Hui Zhou, Ye Guo, Liqun Zou, Junning Cao, Yunhong Huang, Jie Jin, Liling Zhang, Haiyan Yang, Xiaojing Xing, Huilai Zhang, Yanyan Liu, Xiaoli Zhu, Teng Fang, Hangjun Dai, Qinzhou Qi, Jason Yang
Journal: Journal of Clinical Oncology (2022)

7501 Background: R/R ENKTL is a rare and aggressive type of non-Hodgkin’s lymphoma. Responses to chemotherapy after failure of prior asparaginase-based regimen were not durable with a median OS of &lt; 7 months (mos) and 1-year OS rate of &lt; 20% (Lim et al, Ann Oncol 2017; Bellei et al, Haematologica 2018). The only targeted therapy approved in China for R/R peripheral T cell lymphoma (ENKTL included) showed an ORR of 18.8% and a CR rate of 6.3% (Shi et al, Ann Oncol 2015). Here, we present the primary analysis from GEMSTONE-201, the largest registrational study reported to date to evaluate an anti-PD-L1 mAb in R/R ENKTL. Suge received breakthrough therapy designation from US FDA in 2021 for adult R/R ENKTL pts based on preliminary data of this study. Methods: Pts with ECOG PS of 0/1 and histologically confirmed ENKTL who failed prior asparaginase-based regimen were enrolled. Pts accepted suge at 1200 mg Q3W, iv, for up to 24 mos, until progression, death, or withdrawal from study. The primary endpoint was ORR (CR+PR) assessed by independent radiological review committee (IRRC) per Lugano 2014 criteria. Key secondary endpoints included investigator-assessed ORR, CR and PR rate, DoR assessed by IRRC and investigators, and safety. Results: As of the data cutoff date, Nov 10, 2021, 80 pts were enrolled and treated (median follow-up of 13.4 mos). Median age was 48 years (range 29-74); 64% were males; 74% had ECOG PS of 1 at baseline; 68% had stage IV disease; about half (49%) received ≥ 2 lines of prior systemic therapy. The median duration of treatment was 5.2 mos (range 0.7-37.4); 23 pts remained on treatment. Among the 78 evaluable pts as per IRRC, ORR was 46.2% (95% CI: 34.8%, 57.8%); 29 (37.2%) pts achieved CR; median DoR was not reached (NR); 12-mo DoR rate was 86%. Investigator’s assessments in 79 evaluable pts were consistent with IRRC results, i.e. ORR of 45.6% (95% CI: 34.3%, 57.2%), 24 (30.4%) pts with CR, and median DoR of NR. The 1- and 2-year OS rates were 68.6% and 54.6%, respectively; median OS was NR (range 0.9-37.2 + mos). Of all pts, 96% (n = 77) had at least one AE. The most common AEs were pyrexia and WBC decreased (n = 24 each, 30%). Grade ≥ 3 AEs occurred in 31 (39%) pts. Suge-related AEs occurred in 61 (76%) pts and were mostly (60%) Grade 1/2. The most common irAE assessed by sponsor was hypothyroidism (n = 13, 16%). SAEs occurred in 18 (23%) pts; 5 (6%) pts had suge-related SAEs which had all been resolved (1 with sequelae). Fatal AEs occurred in 5 (6%) pts and none were suge-related as assessed by investigators. Conclusions: Suge has demonstrated deep and durable anti-tumor activity in R/R ENKTL pts, with a high CR rate and a promising OS benefit trend comparing to historical data. Suge had a well-tolerated safety profile and no new safety signals were detected. Primary analysis indicates that suge could provide a new treatment option to R/R ENKTL pts. Clinical trial information: NCT03595657.